New Build: Main Drain vs. Low Suction vs. Equalizer vs. Skimmers Only

KJohn

Bronze Supporter
Aug 13, 2020
22
Maine
Hello from the frozen (well thawing) north,

Have been planning for a 20x40 rectangular inground with 8.5 ft deep end, and this is a summary of what I’ve read here about installing suction points other than the skimmers. The contestants:

Main Drain -

Good: Can completely drain the pool to change liners (but that’s what, every 10 years? Easy enough to throw in a submersible pump every decade). Can drop the water level for winterizing, chemistry issues, and some repairs (not absolutely necessary, but convenient). Helps with deep end circulation (though returns work better). Can save the pump if water inadvertently drops below skimmers (this can also be accomplished other ways including an automatic filler).

Bad: Adds cost and complexity to install and repair, two more liner penetrations/leak possibility, and can “rob” suction from skimmers which are more important. MD’s don’t seem to do anything that can’t be done fairly easily or better by something else.

Low Suction through a Wall -

Similar to main drain, simpler installation, but can’t completely empty the pool.

Equalizer Pipe to Pool from Skimmer -

Good: Low-water pump protection, ability to drop water level for winterizing and some repairs.

Bad: Another liner penetration, ???

Skimmers Only –

Good: Simplest install, no liner penetrations.

Bad: No low-water pump protection (can use auto fill), need to schlep portable pumps and hoses to drop water level once or twice a year.

I didn’t include entrapment risk, assuming that for new construction compliant dual main drains or low suctions would be installed. And I didn’t include the option of piping the main drain to the skimmer, as it didn’t seem like a great choice.

I’m leaning toward installing an equalizer pipe, though I understand they are going out of fashion.

Please let me know what I’m overlooking!

Thanks, John
 
Last edited:

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
20,933
Bedford, TX
John,

If you have an autofill you don't need anything but the skimmers.

Ask yourself.. How often have I let the water drop below the skimmers? In over 20 years of total operating time I have never had my water drop below the mouth of the skimmer.. and none of my pools have an autofill..

This might be because I look at my pools more often than once a month.. :mrgreen:

If you bring someone in to replace your liner, they are not going to drain your pool using your pump and main drain.. They have a large sump-pump with a 3" hose..

I would get 2 skimmers... no matter what else you do.

Thanks,

Jim R.
 

KJohn

Bronze Supporter
Aug 13, 2020
22
Maine
Thanks Jim for the real life info. Will definitely have two skimmers.

So go with an auto filler to protect against low water, or just keep an eye on things. What about dropping the level to winterize, adjust chemicals, or get access to stuff - wouldn't an equalizer be a fairly simple, inexpensive and not-too-invasive way to accomplish?

Thanks again.
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
20,933
Bedford, TX
John,

I have no problem with having equalizers, I just don't think they are needed..

If I lived in a place where we normally closed our pool, I would own a sump pump for the times I would want to lower my pool water.

If you are the kind of guy that goes on vacation for a month at a time, then an equalizer would be a great back up for an autofill..

Thanks,

Jim R.
 

Dirk

Gold Supporter
TFP Guide
Nov 12, 2017
8,624
Central California
Pool Size
12300
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
I've never tried it, but many folks used to use manual vacuums attached to the suction port in their skimmer. With the right outlet valve back at the pad, it seems that would be a very efficient way to lower a pool's water level, or even drain it. Sump pump is the better solution, though.

Siphons work, too, if you've got the time.

I have a Poolmiser auto-leveler system. It consists of a vault near my skimmer that houses both an auto-fill valve and an overflow pipe. The pipe is just friction-fit into the bottom of the vault. The vault connects to the pool via an equalizer tube. I like this set up for multiple reasons. But if I ever have to drop the water, I just pull the overflow tube out and the pool will drain as much as a foot. Not quickly, but easily.

So that's four ways to drop the level that don't require a drain.

My pool has no drains. I actually had them removed. So I am anti-drain. And I wouldn't build a new pool with drains. I agree with Jim, how many times does the water level get below the skimmer? Never in my case. For $50 you can put a wifi cam on your pool and keep an eye on the water level whenever you want, wherever you are.

And you made a great list for yourself. I would only correct one thing: that a drain doesn't do squat for circulation. It can only move the water that is a few inches away from it. If you want to move deep water, you use deep returns, or point regular returns down.

If I was starting from scratch, I'd have two skimmers, four returns with eyeballs, no drains, and a PoolMiser auto-leveler.
 

KJohn

Bronze Supporter
Aug 13, 2020
22
Maine
Good points Dirk, thanks.

I was actually looking at PoolMiser yesterday, and it looks like a great setup. I have a call into them to see how it can be winterized.
 

Dirk

Gold Supporter
TFP Guide
Nov 12, 2017
8,624
Central California
Pool Size
12300
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
I don't know if this tip can be used for winterizing, but a PoolMiser doesn't need to be near the pool. It can be up to 30' away. Maybe back at the pad, or by a hose bib. The equalizer pipe would span the 30', but that could be blown out, and wouldn't need to be insulated. The PoolMiser's water supply line would, but by placing the PM closer to the water source, the insulation requirements would be considerably less.
 

KJohn

Bronze Supporter
Aug 13, 2020
22
Maine
I did notice that PM could be placed at a distance from the pool, but wasn't sure how that would work with the deck pitch - seems like the water level in the cannister (same as pool level) might get too high as the grade drops? Thanks for pointing that out though. I do think I'll put the PM on the shopping list.
 

Dirk

Gold Supporter
TFP Guide
Nov 12, 2017
8,624
Central California
Pool Size
12300
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
The PM works on the "water seeks its own level" principle through its equalizer pipe, so no matter where its installed, it must be about level with the pool. Uphill or downhill wouldn't work.
 

Enjoying this content?

Support TFP with a donation.

Give Support